CIRCULATING HEMOCYTES AND PHARYNGEAL EXPLANTS OF STYELA-CLAVA RELEASEHEMAGGLUTININ IN-VITRO

Tunicate blood cells are a mixed population, thus experiments that ass ay their immunodefense responses, such as release of hemagglutinins, w ere done to isolate different functional hemocytic types. Two sources of hemocytes from Styela clava were used, the hemolymph and the pharyn x (the hemopoietic organ). Hemolymph centrifuged through a discontinuo us Percoll gradient yielded four distinct bands of hemocytes. After in cubation at 15 degrees C, circulating hemocytes and those from pharyng eal cultures released hemagglutinin after 2 and 30 days. Highest titer s were found in B1 (hyaline and compartment cells), B3 (hyaline cells and eosinophil granulocytes), and B4 (hyaline cells and debris). Hemag glutinating activity was also found after homogenization of the hemocy te bands except for B2. Homogenate of fresh pharyngeal explants showed no hemagglutinating activity but tissues cultured for 30 days had tit ers up to 1:16. These results are unique in pointing out the capacitie s of two tunicate hemocyte types (circulating, pharyngeal) to: release hemagglutinin in vitro and assign at least one functional property to discrete populations.